Biochemical changes during valine production by Aerobacter aerogenes.

The typical chemical changes taking place during valine production by A. aerogenes in a synthetic medium have been investigated. The principal carbon and nitrogen sources, sucrose and urea, respectively, have been found to be almost exhausted during an incubation period lasting 90 h. While the carbon compound was depleted right from the start of formentation, the disappearance of urea was noticeable after 16 h of incubation. The formation of valine in the broth started between 24 and 40 h of incubation connected with the rapid utilization of urea. The pH value of the broth was found to glide down from an initial value of 7.5 to 6.4 within 24 h then rising again to 7.5 during 64 h and further to 8.0 in 90 h of incubation.